An Automatic Gain Control (AGC) circuit may be required when amplitude of an input signal of a Radio Frequency (RF) receiver varies over a wide dynamic range to provide a relatively constant amplitude so that circuitry of the RF receiver following the AGC circuit requires lesser dynamic range. For example, anti-jamming receivers may require the AGC circuit therein to be capable of increasing the amplitude of the input signal at one rate, and decreasing the amplitude at a significantly different rate. Attack time may refer to the time in which the AGC circuit decreases the gain of one or more Variable Gain Amplifiers (VGAs) in the RF receiver when an unwanted signal appears, and decay time refers to the time in which the AGC circuit increases the gain of the one or more VGAs when the unwanted signal disappears.
A transconductance amplifier utilized in the AGC circuit may have an input offset that is strongly dependent on the ratio of current limits thereof. Moderate differences between the positive and the negative current limits of the transconductance amplifier may generate large offsets, thereby causing serious errors in the amplitude control. The amplitude control errors may degrade the overall performance of the RF receiver.